Abstract
OBJECTIVE: Systematic evaluation of the effectiveness of innovative care concepts for diabetes, taking into account heterogeneity of study results. DESIGN: Systematic review, meta-analysis and meta-regression analysis. METHOD: Medline, CINAHL and PsycINFO were searched for reviews and empirical studies into adult patients with diabetes in whom interventions were used that consisted of a minimum of 2 components from the Chronic Care Model. In the meta-analysis, a random-effects model was used to pool results on HbA1c and systolic blood pressure. Meta-regression analysis was used to examine the extent to which 3 differences in study design - (a) methodological quality, (b) length of follow-up, and (c) number of intervention components - could explain the heterogeneity in effect measures. RESULTS: The reviews (n = 15) generally reported modest improvements in glycaemic control. The empirical studies (n = 56) differed greatly in the direction and magnitude of measured effects on HbA1c (mean: -5 mmol/mol; 95% CI: -7- -3.5) and systolic blood pressure (mean: -2.8 mmHg; 95% CI: -4.7- -0.95). Variation in methodological quality between the studies could not explain this. Short-term studies (< 1 year) reported more positive results than longer-term studies (>/= 1 year), but this difference was not significant. The variation in the number of intervention components explained 8-12% of the heterogeneity in effects of diabetes care innovations. CONCLUSION: Diabetes care interventions that include more than 2 components have the most positive effects on clinical outcomes. Considering the connection between length of follow-up and results as well as the fact that the targets of these innovations focus primarily on the future, the impact of such interventions should be measured in the long term.
